What are force and torque sensors used for on a robotic arm?
Force and torque sensing helps a robot measure interaction with its environment. Depending on the system, sensing may come from a wrist-mounted sensor, joint sensors, or estimates derived from the drive system. These approaches provide different information and should not be treated as interchangeable.
What this means in practice
Applications include surface finishing, insertion, contact detection, and controlled pressing. The program can use measured forces to adjust motion or identify an unexpected condition. Measurement quality depends on sensor range, calibration, tooling, load compensation, and process dynamics.
Distinguish contact forces from other influences
Sensor readings can include the effects of tool weight, acceleration, and contact with the workpiece. The controller or application must interpret them appropriately. Incorrect load compensation can make the apparent contact force different from the force the process is intended to regulate.
Define acceptable readings for each phase of the task, rather than relying on one threshold for the entire cycle. Test expected variation and abnormal contact. Sensor capability, bandwidth, mounting stiffness, and control behavior must match the operation; sensing alone does not guarantee successful insertion or finishing.
Key points
Check which quantities are measured and their stated performance.
Calibrate for the actual tool and mounting configuration.
Define acceptable process forces and a response to abnormal readings.
Practical example and next step
In a fitting operation, force feedback can help distinguish normal contact from misalignment. It does not eliminate the need for suitable fixtures or part tolerances. A general process sensor also should not be assumed to provide a certified safety function.